Closed lubrication system

ABSTRACT

A portable electric device comprising a housing having an electric motor disposed therein. The motor includes a rotatable shaft carried by bearings supported upon the housing. The motor shaft rotates an output member which carries a rotatable tool bit. In addition, the motor shaft actuates a hammer mechanism adapted to deliver a series of longitudinal hammer blows to the rear end of the tool bit. The hammer mechanism is constructed in a novel manner to insure distribution of lubricating grease throughout.

- United States Patent Inventor Robert G. Moores, Jr.

Cockeysville, Md.

Appl. No. 77,643

Filed Oct. 2, 1970 Patented Dec. 28, 1971 Assignee The Black and Decker Manufacturing Company Towson, Md.

CLOSED LUBRICATION SYSTEM 8 Claims, 3 Drawing Figs.

U.S. Cl 173/117, 92/155,173/119 Int. Cl B25d 11/00 Field of Search [56] References Cited UNITED STATES PATENTS 1,825,072 9/1931 Keller 173/117 2,285,702 6/1942 Forss 173/118 3,570,628 3/1971 Rodgers 92/155 Primary Examiner-James A. Leppink Attorneys-Leonard Bloom, Joseph R. Slotnik and Edward D.

Murphy ABSTRACT: A portable electric device comprising a housing having an electric motor disposed therein. The motor includes a rotatable shaft carried by bearings supported upon the housing. The motor shaft rotates an output member which carries a rotatable tool bit. In addition, the motor shaft actuates a hammer mechanism adapted to deliver a series of longitudinal hammer blows to the rear end of the tool bit. The hammer mechanism is constructed in a novel manner to insure distribution of lubricating grease throughout.

CLOSED LUBRICATION SYSTEM SUMMARY or THE INVENTION The present invention is directed to a novel construction which facilitates thorough and complete grease lubrication of a hammer mechanism in a rotary hammer. The hammer mechanism is substantially a closed system communicated with a grease reservoir and theparts are constructed so that during normal operation, lubricating grease is constantly redistributed throughout the system to insure thorough lubrication of all the parts. The invention contemplates no additional parts and utilizes the intercooperation of the hammer mechanism parts to fulfill the objects herein set forth.

Main objects, therefore, of the present invention are to provide a novel closed lubrication system for use in a hammer mechanism of a powered, rotary hammer wherein the component parts of the hammer mechanism are thoroughly grease lubricated and the grease constantly redistributed during use of the tool by means of intercooperation of the component hammer mechanism parts.

Further important objects of the present invention are to provide a novel closed lubrication system of the above character which is relatively inexpensive to manufacture, simple and durable in construction, and reliable in performance.

Other objects and advantages of the present invention will become more apparent from a consideration of a detailed description to follow taken in conjunction with the drawings annexed hereto.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view illustrating a portable electric rotary hammer embodying the present invention;

FIG. 2 is an enlarged view, partly broken away and partly in section, of the construction of-FIG. l; and

FIG. 3 is a sectional view of the construction of FIG. 2 taken along the line 3-3 thereof.

BROAD STATEMENT OF THE INVENTION 'Broadly described, the present invention relates to a rotary hammer comprising a housing having a drive motor therein, a tool bit supported upon said housing, a hammer mechanism adapted to deliver longitudinal hammer blows to said tool bit, transmission means interconnecting said drive motor and said hammer mechanism, said hammer mechanism including an elongated barrel fixed in said housing, a ram in said barrel and movable longitudinally thereof and axially of said bit, a coil spring closely disposed to the internal periphery of said barrel and normally biasing said ram toward engagement with said tool bits, said transmission means including rotatable means adapted to move said ram away from engagement with said tool bit, said coil spring normally tending to rotate with said rotatable means, a lubricating grease reservoir in communication with the interior of said barrel, whereby movement of said ram tends to displace grease in one direction longitudinally of said barrel, said spring rotating in a direction whereby to cooperate with the inner peripheral surface of said barrel and feed said grease axially thereof between said spring and said barrel in a direction opposite said one direction, whereby to continually redistribute said lubricating grease within said barrel.

In another aspect, the present invention relates to a portable rotary hammer comprising a housing having an electric motor disposed therein, an elongated barrel fixed within said housing and having a ram rotatably and reciprocably disposed therein, a coil spring in said barrel and normally biasing said ram in one direction longitudinally of said barrel, transmission means interconnecting said motor and said ram, whereby to rotate said ram and move it in another longitudinal direction opposite said one direction, said coil spring being rotatable with said ram, said rotating and reciprocating ram tending to move lubricating grease within said barrel in said one longitudinal direction and radially of said ram, said rotating spring tending to move said lubricating grease by threading action in said another longitudinal direction.

DETAILED DESCRIPTION Referring now more specifically to the drawings, a portable electric rotary hammer embodying the present invention is illustrated generally at 11 in FIGS. 1 and 2 and is seen to include a motor housing 13 having an end handle 15 rigid therewith. An electric motor 17 is disposed within the housing 13 and has a motor shaft 19 rotatably supported for and aft by bearings (not shown). The motor 17 is powered from an electric source connected thereto by a line cord 18 and is controlled by a trigger 20 on the end handle 15.

The forward end of the shaft'19 extends through a gear case cover 23 and into a gear case 25. A gear train (not shown) located within the gear case 25 interconnects the shaft 19 and a tool bit supporting member 27 A tool bit 29 has a noncircular shank portion 31 slidably and nonrotatably supported within a complimentary configured opening 33 in the tool bit supporting member 27. Thus, when the motor 15 is energized, the tool bit supporting member 27 and tool bit 29 are rotated.

A cupshaped barrel member 39 has a radial flange 40 at its forward end secured to the gear case cover 23 by screws 41. The barrel 39 encompasses a collar 53 fixed therein and the rearward end of the bit supporting member 27 and extends rearwardly thereof in general parallel relation with the motor 15. A ram 42 is slidably'disposed within the barrel 39 and has a reduced diameter forward portion 43 extending into a cavity 35 in the rearward portion of the bit carrying member 37 and is keyed thereto for rotation therewith by balls 45. The ram 42 is normally biased in a forward or right hand direction, as seen in FIG. 2, by a relatively heavy, coil, compression spring 47. The ram 42 is movable rearwardly or toward the left as seen in this Figure by means of a cam-lift mechanism which comprises cooperating spiral cam surfaces 49, 51 on the ram 42 and the fixed collar 53, respectively. Thus, when the bit supporting member 27 is rotated by the motor 15, it rotates the ram 42 through the balls 45 and, by means of the cooperating cam-lift surfaces 49, 51 the ram 42 is gradually moved rearwardly and compresses the spring 47. Thereafter, the cam surfaces 49, 51 move past each other whereupon the spring 47 drives the ram 42 forwardly or toward the right whereupon the forward portion 43 of the ram 42 impacts against the shank 31 of the bit 29. Continued operation of the motor 15 repeats this sequence.

It will be appreciated that lubrication of the component parts of the hammer mechanism is highly important to efficient operation and long life of the parts. To this end, a grease carrier 63 is fixed within the rear end of the barrel 39. A reservoir 61 is formed in the carrier 63 and is covered by a cap 65 fitted within the end of the member 63. The ram 42 has a reduced diameter rearward portion 67 which extends slidably through an opening 69 in the member 63 and into the grease reservoir 61.. A quantity of grease 71 is provided in the reservoir 61 and is circulated throughout the confines of the barrel 39.

In use, the bit supporting member 27 is rotated and rotates the bit 29. At the same time, the ram 42 is rotated and moved rearwardly by the cooperating cam-lift surfaces 49, 51 and thereafter moved forwardly under the force of the compression spring 47 and delivers a hammer blow to the bit 29. Since the rear end of the barrel 39 is closed by the cap 65, the grease 71 works its way forwardly in the barrel 39 toward the bit shank 31. In addition, quite often the tool 11 is held in a vertical position during operation so that the grease 71 tends to flow by gravity toward the front end of the tool and the bit shank 31. In order to counteract this tendency for all the grease 71 to accumulate at the forward end of the barrel 39 and possibly leak out past the bit shank 31, and to insure that the grease is continuously redistributed throughout the barrel 39, use is made of the coil spring 47 which normally tends to rotate with the rotating ram 42.

As shown in FIG. 2, the coil spring 47 is disposed in relatively close relation to the interior surface of the barrel 39. In normal use of the tool 11, the coil spring 47 turns with the ram 42 in a counterclockwise direction, as viewed from the front of the tool 11. Since the spring 47 is helical in configuration, this turning movement causes it to act like a screw so that the grease 71 which is trapped between the spring 47 and the interior of the barrel 39 is fed rearwardly or toward the left as seen in FIG. 2. In addition, the rotating ram 42 and spring 47 tend, by centrifugal force, to throw the grease 71 radially outwardly against the interior of the barrel 39. This, coupled with the normal tendency of the grease to flow forwardly in the barrel 39 serves to continuously redistribute this grease throughout the barrel 39 and thoroughly and completely insures lubrication of all the component parts of'the hammer mechanism throughout use of the tool 11. In addition, this is achieved without the need for any extra parts and employs the normal operating features of the individual component parts of the hammer mechanism. Thus, long life and efficient operation of the too is insured.

By the foregoing, there has been disclosed a novel sealed and lubricating system for an impact tool calculated to fulfill the inventive objects herein above set forth, and while a preferred embodiment of the present invention is illustrated and described in detail above, various additions, substitutions, modifications, and omissions may be made thereto without departing from the spirit of the invention.

We claim:

1. A rotary hammer comprising a housing having a drive motor therein, a tool bit supported upon said housing, a hammer mechanism adapted to deliver longitudinal hammer blows to said tool bit, transmission means interconnecting said drive motor and said hammer mechanism, said hammer mechanism including an elongated barrel fixed in said housing, a ram in said barrel and movable longitudinally thereof and axially of said bit, a coil spring closely disposed to the internal periphery of said barrel and normally biasing said ram toward engagement with said tool bit, said transmission means including rotatable means adapted to move said ram away from engagement with said tool bit, said coil spring normally tending to rotate with said rotatable means, a lubricating grease reservoir in communication with the interior of said barrel, whereby movement of said ram tends to displace grease in one direction longitudinally of said barrel, said spring rotating in a direction whereby to cooperate with the inner peripheral surface of said barrel and feed said grease axially thereof between said spring and said barrel in a direction opposite said one direction, whereby to continually redistribute said lubricating grease within said barrel.

2. A portable rotary hammer comprising a housing having an electric motor disposed therein an elongated barrel fixed within said housing and having a ram rotatably and reciprocably disposed therein, a coil spring in said barrel and normally biasing said ram in one direction longitudinally of said barrel, transmission means interconnecting said motor and said ram, whereby to rotate said ram and move it is another longitudinal direction opposite said one direction, said coil spring being rotatable with said ram, said rotating and reciprocating ram tending to move lubricating grease within said barrel in said one longitudinal direction and radially of said ram, said rotating spring tending to move said lubricating grease by threading action in said another longitudinal direction.

2. A device as defined in claim 1 wherein said ram includes a portion extending into said reservoir.

4. A device as defined in claim 1 wherein said ram rotates with said rotatable means, whereby to propel said grease radially outwardly against said barrel.

5. A device as defined in claim 1 wherein said spring surrounds a reduced diameter portion of said ram, said ram being keyed to said rotatable means to rotate therewith, said ram being aperture to displace grease radially outwardly thereof by centrifugal force during operation of said tool.

6. A device asdefined in claim 2 wherein said spring is disposed in closely spaced relation to the interior surface of said barrel, whereby to cooperate therewith during operation of said tool to move said grease in said another longitudinal direction.

7. A device as defined in claim 2 wherein said ram includes 

1. A rotary hammer comprising a housing having a drive motor therein, a tool bit supported upon said housing, a hammer mechanism adapted to deliver longitudinal hammer blows to said tool bit, transmission means interconnecting said drive motor and said hammer mechanism, said hammer mechanism including an elongated barrel fixed in said housing, a ram in said barrel and movable longitudinally thereof and axially of said bit, a coil spring closely disposed to the internal periphery of said barrel and normally biasing said ram toward engagement with said tool bit, said transmission means including rotatable means adapted to move said ram away from engagement with said tool bit, said coil spring normally tending to rotate with said rotatable means, a lubricating grease reservoir in communication with the interior of said barrel, whereby movement of said ram tends to displace grease in one direction longitudinally of said barrel, said spring rotating in a direction whereby to cooperate with the inner peripheral surface of said barrel and feed said grease axially thereof between said spring and said barrel in a direction opposite said one direction, whereby to continually redistribute said lubricating grease within said barrel.
 2. A portable rotary hammer comprising a housing having an electric motor disposed therein an elongated barrel fixed within said Housing and having a ram rotatably and reciprocably disposed therein, a coil spring in said barrel and normally biasing said ram in one direction longitudinally of said barrel, transmission means interconnecting said motor and said ram, whereby to rotate said ram and move it is another longitudinal direction opposite said one direction, said coil spring being rotatable with said ram, said rotating and reciprocating ram tending to move lubricating grease within said barrel in said one longitudinal direction and radially of said ram, said rotating spring tending to move said lubricating grease by threading action in said another longitudinal direction.
 3. A device as defined in claim 1 wherein said ram includes a portion extending into said reservoir.
 4. A device as defined in claim 1 wherein said ram rotates with said rotatable means, whereby to propel said grease radially outwardly against said barrel.
 5. A device as defined in claim 1 wherein said spring surrounds a reduced diameter portion of said ram, said ram being keyed to said rotatable means to rotate therewith, said ram being aperture to displace grease radially outwardly thereof by centrifugal force during operation of said tool.
 6. A device as defined in claim 2 wherein said spring is disposed in closely spaced relation to the interior surface of said barrel, whereby to cooperate therewith during operation of said tool to move said grease in said another longitudinal direction.
 7. A device as defined in claim 2 wherein said ram includes reduced diameter front and rear portions, said front portion being adapted to hammer upon tool bit means supported upon said housing, said rear portion extending through said coil spring.
 8. A device as defined in claim 7 which includes a grease reservoir in said barrel, said ram rear portion extending slidably into said reservoir. 